Mill mandrel bar



Oct. l5, 1935.

W. BARK ET AL MILL MANDREL BAR Filed June 2, 1952 m. WMWMMMWMMWMWMMWMMMMNMUWW and OLOF FT G450/V.

Patented ci.' 15, 1935 Nro STATES Prem' erica MILL MANDREL aan.

Application June 2, 1932, SerialvNo. 615,017 zciaims. (c1. sei- 13) This invention broadly relates to the manufacture of tubes and specifically to the mandrel bars of tube mills and machinery. At present, these are constructed with a loose inside Water 5 cooling pipe which thrashes violently about as a tube is being rolled, and frequently fractures itself. The present bar is intended to obviate this objectionable feature and, in addition, to provide an improvement in stiffness and general resistlo ance to thrust. The invention also covers an improved tube rolling method which will be disclosed after describing the new bar.

The accompanying drawing illustrates a specific example of the mandrel bar and also the new l5 rolling method,

Figure l being a side elevation, and

Figure 2 a longitudinal cross-section.

These various iigures show a tube I containing a second and smaller tube 2. Inside of this sec- 20 'ond tube is a watercooling pipe 3; which contains a. compressed air pipe 4. A-number of apertured annular bracing members 5 are spaced throughout this assembly between the tubes I and 2.

Preferably, these are Welded to the inside tube 25 2 because this facilitates the bars assembly during its construction. These members 5 serve to distribute bending stresses between the tubes I and 2 so that the bars tendency to whip is greatly decreased. Similar but smaller bracing mem- 30 bers 6 are spaced along between the pipe,3 and the tube 2. These are alsov preferably Welded to the innermost member, the pipe 3, and are spaced so that when the bar is assembled they will be in line with the member 5 and willhold the pipe 35 .3 at the bars axis.

The right-hand end of the bar is carried by a mounting 1 which works against a thrust block 8. Its left-hand end is xed to a head 9 which carries a pin I on which a mandrel Il may be 40 mounted. The working rolls I2 are only diagrammaticallyiillustrated as they are conventional. J j

The primary diil'erence between the head end of this bar and others is thatzthe pin Ill is bored 45 so that theg compressed air pipe 4 can extend through to its tip. This tip is constructed with orifices I3 whose function will be explained shortly. The bore in the pin I0 has an enlarged portion Il which receives the cooling water eject- 50 ed from the pipe 3. Tins water' can, of course, ow back from this portion lI4 and circulate through the entire bar as the spacing members 5 and 6 are all apertured for this purpose. Apertures I 5 at either end of the tube 2 provide inlets 55 and outlets so that circulation is established within this tube also. y

It is apparent that the bar will be extremely stil! and non-whipping. Bending stresses will be distributed equally throughout the various parts, the bar being in eect a structural column. It is impossible for the water cooling tube 3 to thrash or shake about as it is supported at shortly spaced points. The play between this pipe and 5 I its contained air supply pipe 4 is too small to permit excessive whipping. In any event, the air pipe will be rmly held by the hydrostatic pressure about it.

Much diiliculty has been experienced with ex- 10 cessive scale formingon the inside of tubes being rolled, especially in the larger sizes, the usual eiorts to blow the scale from end to end of the tube just prior to rolling having pro en more or less ineffectual. However, when using this new l5 mandrel bar itis possible to eject compressed air directly against the inside surface of the tube just about to pass over the mandrel I I. Naturally, the effect of this direct uid impingement method is much greater than that obtained by merely blowing air through the pipe from one end. 0f course. this rolling method may be performed with any mandrel bar which is altered by the addition ofan air pipe communicating with the nose of its mandrel and is not necessarily limited to the use of air, as steam or other iiuid under pressure may be used. 'Ihe orices in the pin are constructed so that this fluid strikes the pipe at high velocity.V

Although a specic form of the new mandrel bar has been shown and described in accordance with the patent statutes, it is not intended to limit the scope of the invention exactly thereto except as dened by the following.

We claim:

1. A mandrel barincluding a. plurality of superimposed tubes, a plurality oi' spaced annular and apertured bracing members arranged in circumferential alinement betweenA said tubes, s. mandrel supporting pin carried at one end of said tubes, a water pipe within the innermost one oi 40 said tubes, means for supporting said pipe at said tubes axes, a compressed uid pipe in said water pipe and communicating with the extreme end ofsaidvpin and apertures in the walls of all the inner ones of said tubes.

2. A mandrel bary for tube mills, including a tubular body.. a -second'tubular body within the rst named tubular body and opening thereinto, a Aconduit within said second tubular body, the rst named body being provided with a means 50 for mounting a mandrel having a longitudinally extending conduit communicating with the i'lrst named conduit, and a series of spaced braces between said tubular bodies throughout their lengths. 55

WILLIAM BARK.

JAMES V.y MAZURIE.

OLOF F. OLSONr 

